Page:The origin of continents and oceans - Wegener, tr. Skerl - 1924.djvu/183

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CHAPTER XI

FOLDS AND RIFTS

As far back as 1878, A. Heim had developed in his classical paper, “Untersuchungen über den Mechanismus der Gebirgsbildung,” the idea that the great chains of folded mountains originated in a considerable compression of the earth’s crust. This doctrine was amplified by the discovery of the imbricated sheet folds in the Alps which indicated a still more powerful compression.

According to this new conception, to which he assented, A. Heim now calculated the compression of the Alps, which he had first estimated at a half, to be from a quarter to an eighth. Later, Ampferer assumed flow-movements of the deeper layers which, directed towards each other from both sides, pass downwards under the mountain chain and carry the upper beds passively along with them (under-currents). Koszmat has quite recently referred to the curvature of the mountain chains, and their fan-shaped association at many places. This appears to him only explainable by great horizontal displacements; “many features in the relief and structure of the earth seem to make it certain that an explanation of mountain-building must take into account enormous tangential movements of the crust.[1] This conception is in itself almost identical with that of the displacement theory,

  1. F. Koszmat, “Erörterungen zu A. Wegener’s Theorie der Kontinentalverschiebungen,” Zeitschr. d. Ges. f. Erdk. zu Berlin, p. 103, 1921.

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